Researchers working in the magnetic recording industry have recently begun focusing their efforts on developing thin film heads having a so-called integrated head/flexure/conductor structure for reading and writing of information to a disk medium. For example, such a magnetic head structure is disclosed in U.S. Pat. No. 5,041,932. In this type of recording technology, a magnetic pole element is embedded within the body of the magnetic recording head. Advanced performance is achieved in these types of magnetic recording heads by including a contact pad region which is in non-catastrophic, continuous sliding contact with the surface of the recording medium. The contact pad includes a working surface portion which is extremely small—on the order of about 20×30 microns The working surface portion of the contact pad actually touches the disk during normal operation.
One of the problems associated with recording heads which are in contact with the recording medium is that a substantial amount of debris is generated by the sliding action of the head against the surface of the disk. As well as being a direct result of slider-disk micro-interactions, dust and dirt from both the environment and the drive can also accumulate on and around the contact pad region. Eventually, this particulate matter finds its way into the interface between the contact pad and the disk, leading to adverse effects such as signal modulation caused by particle induced fluctuations in the head-disk spacing, and increased wear resulting from debris entering the friction zone and scratching the working surfaces.
The problem with debris accumulation is also present in more conventional slider designs in which the head flies above the surface of the disk. By way of example, In a typical magnetic recording system, the rotation of the rigid disk causes the magnetic head or slider to become hydrodynamically lifted above the surface of the recording medium. This hydrodynamic lifting phenomena results from the flow of air produced by the rotating magnetic disk; it is this air flow which causes the head to “fly” above the disk surface. Of course, when the rotation of the magnetic disk slows or stops, the head element is deprived of its buoyancy and it lands on the surface of the disk. Repeated starting or stopping of the disk causes the recording head to be dragged across the surface of the disk over and over again during the “take-off” and “landing” phases of its flight.
The current trend in the industry is toward increasing the magnetic signal strength by lowering the slider flying height. In the conventional type of magnetic recording head described above, this means that the separation between the head and the disk is radically reduced. For instance, very low flying heights on the order of 1 to 3 microinches are becoming increasingly common. Obviously, reducing the separation between the head and the disk medium results in increased abrasive wear. Thus, in both the near-contact (flying low, e.g., at 1 to 3 microinches) and the in-contact types of recording systems, debris accumulation is a significant problem.
It should be understood that in the conventional type of magnetic recording head which flies above the surface of the disk (i.e., near-contact recording system), the working surface which touches the disk normally comprises two or more rails having flat bottom surfaces. For example, sliders of this type are disclosed in U.S. Pat. Nos. 4,870,619; 4,961,121; 4,926,274; and 4,709,284. To increase the hydrodynamic lifting force, many sliders have a front taper as described in U.S. Pat. No. 4,939,603. Other designs include a sloping working surface. In either case, the taper and/or slope are in the vertical direction; that is, perpendicular to the disk surface. Other prior art designs include the so-called slider camber and crown—characterized by their vertical slopes in both the longitudinal and cross directions, respectively. This latter type of design is usually selected based on considerations of smaller contact area so as to reduce the problem of stiction. The drawbacks to these designs however include the requirement for a higher take-off velocity and an, increased wear rate.
What is needed then in both the near-contact and in-contact recording technologies is a slider design which is able to reduce the effect of debris accumulation so as to improve the wear rate in magnetic recording signal strength. As will be seen, the present invention comprises a magnetic head slider suitable for use in in-contact and near-contact recording systems in which the leading edge of the working surface has a narrower width as compared to the trailing edge. In several embodiments described below, the contact pad or slider rails assume either a “V” or “U” shape in the direction of flying or sliding.
Other prior art known to Applicant includes U.S. Pat. No. 4,757,402 which discloses a slider presenting a substantially equal cross sectional area to an air film moving with the media as the head is skewed slightly relative to the oncoming air flow.